The present invention relates generally to closed loop feedback control systems, and more particularly to a PID controller that is based on a non-uniform two-point sampling methodology, that generates a smooth control output signal regardless of changing control conditions and parameters, and that utilizes trapezoidal integration techniques to insure loop control accuracy and stability. The smooth control output signal is generated from an input signal that is filtered through a digital filter including both an adaptive amplitude filter and a low pass frequency filter.